Spray booth



A. H. MEYER Jan. 22, 1952 SPRAY BOOTH 2 SHEETS-SHEET 1 Filed Oct. 9,1946 IN V EN TOR. j 1%, 1 94/7 W A. H. MEYER SID-RAY BOOTH Jan. 22, 19522 SHEETS-SHEET 2 Filed Oct. 9, 1946 INVENTOR. I 2/ Z1/%% A BY M PatentedJan. 22, 1952 SPRAY BOOTH Alva H. Meyer, Arlington Heights, 111.,asslgnor to Benjamin Electric Manufacturing Company, Des Plaines, Ill.,a corporation of Illinois Application October 9, 1946, Serial No.702,114

3 Claims. 1

This invention relates to improvements in spray booths, particularlythose employed for spraying reclaimable material.

In the art of spray finishing, the object to be finished is placed on asuitable platform within a booth, the front of the booth being open andthe remaining sides and top forming a hood to which a stack isconnected. An exhaust fan in or near the stack is effective to removeany fumes, atomized paint or lacquer, or particulate sprayable materialfrom the spraying region, the principal object being the avoidance ofinhalation of such fumes or material by the operator. In the art ofvitreous or porcelain enameling particularly, the material sprayed onthe object and the conditions of operation of prior apparatus are suchthat only about fifty per cent of the material adheres to the object,the principal part of the remainder being wasted through the stack, andsome small part being deposited on the interior of the booth wherefromit may be reclaimed. However, under those conditions-for example,scraping the material from the walls and floor of the boothadulterationmay readily occur, and the expense of separating out the adulterant isoften costlier than the value of the reclaim.

One process to which the instant invention is specifically applicable isthat of applying vitreous or porcelain enamel to metal surfaces-forexample, reflectors of the type used in electric lighting, tubs forwashing machines, and so forth. These are conventionally of metal towhich the usual ground coat is first applied by dipping or spraying,after which the glazing material is applied by means of a spray gun.Many glazing formulas are used, each manufacturer having his ownconception of the proportions to be used, the art being largely anempirical one. In so far as the present disclosure is concerned, thecomposition isimmaterial, the essence of the invention residing in thereclamation of the material for reuse. As sprayed, the material containsa fluid element serving as a vehicle for, or as a component with,certain particulate materials, such as frit, whiting, clays, and otheringredients. After spraying, the fluid element evaporates so that aconsiderable part of the solids settle on the floor or other parts ofthe booth.

One prior method has been to utilize a water bath through which thestack draft draws the surplus material. In this form the solids settleto the bottom of the container and the fumes are exhausted toatmosphere. Another method employs a water spray or water curtain todislodge the particles from the air stream. Both modes of reclamationaredecidedly unsatisfactory, since the water dissolves the clayey as wellas other materials and renders the reclaim unfit for use unless it isrestored by the addition of the robbed elements. Moreover, a water bathinvolves a substantially larger exhaust fan motor.

Of importance also is the need for preventing emission of the frit orother siliceous material through the stack, which would otherwise createan atmospheric condition about the enameling room conducive tosilicosis.

In order to avoid the shortcomings of prior methods and means heretoforepointed. out, the principal object of my invention is the provision, inconjunction with a spray booth, of a perforate ballle or screeninterposed between the spraying site and the stack, upon which baflie asubstantial percentage of the particulate sprayed material may settle tobe reclaimed, the material separating the apertures beingof such area asto interfere with normal stack draft only to the minimum extent.

Another object is to provide a baflle, as aforesaid, comprised of aplurality of spaced, like screens, the apertures 'of each of which arestaggered with respect to the next adjacent screen to increase theproportion of reclaim.

An additional object is to provide a plurality of screens for thepurpose aforesaid, arranged in series in the air stream through thebooth.

Another object is to provide a disposition of such screens in theexhaust duct which will act at widely spaced-apart points in the airstream to afford primary and succeeding particle-separating functions.

Still another object is to provide means for removing the materialadhering to the screens by vibration. g I

A further object is to position the baffle aforesaid in a chamberinterposed between the spray ing site and stack, and which chamber isprovided with a door through which the reclaim may be removed.

Another object is to provide reclaiming screens, as aforesaid, which arethemselves finished in porcelain enamel or a'similar glazed finish whichis effective to cause temporary adhesion of the particulate materialthereto, but which. will not resist removal of the same upon vibrationof the screens.

In the drawings, which show one form in which the invention may beembodied in practice:

Fig. l is a side elevational view of the spray booth showing theassembly of the baflle in relation thereto, and with the right sidepanel of the booth removed for convenience in illustration;

Fig. 2 is a front view of the booth showing the widthwise extentof thebaffle;

Fig. 3 is a plan view of the bafiie assembly in its relation to thebooth;

Fig. 4 is across-sectional line 44 of Fig.3;

Fig. 5 isa partial detail of the bafile screens; and V Fig. 6 is across-sectional detail taken on the line 6-B of Fig. 5 to indicate thenature of the deposit on a screen.

The invention is capable .of adaptation to a spray booth of any typeusually employed for view taken on the spraying of reclaimable materialas' he'reinbefor'e discussed, and by way of example I have shown a boothcomprising a fioor, side walls, a roof the supports 31 in order that thescreen assembly may float and avoid agitation and consequent looseningof parts of the booth while the screens are vibrated in a manner to bepointed out, and

may also, by fore and aft shifting thereof, be removed from the supports31 for maintenance.

In operation excess sprayed material is carried by the air stream, asalready explained,

and a rear Wall of sheet metal or other'suit'able panel material, theframework being of angle iron as shown. For supporting-the articles in aposi tion convenient for spraying, afixed metal sheathed, woodenplatform It], or a revoluble platform (not shown) ,-may be provided,the-op erator standing'in-frontofthebooth, i. e., to the left side ofFig. l.

In order to provide duplex action on the part of a single assembly ofscreens, provision ismade to direct the air and its suspended matter ina tortuous path, as indicated by arrows in Fig. 1, an inclined baiile II being mounted in the spraying chamber, as'shown; to direct the airstream through the lower portion of the'bafile assembly into a'rearchamber l2, the air stream-then flowing through the upper portion of thebafile and thence to the stack l3. An exhaust fanof any known type ismounted with its impeller within the stack, the driving motor and beltbeing in dicated at M.

The baffie assembly, best seen in Figs. 3 and 4, comprises two sections,each including three screens or perforate sheets 2|, Zia and 21b havingsuitably shaped apertures therein, the material illustratedin Fig.5-being ordinary expanded metal having relatively large openingsseparated by the metal lattice. The number of screens is shown as three,although two, ormore than three may be found better under. somecircumstances. However, I have found that in order to obtain maximumreclaiming 'eificiency,.the apertures of one screen should be staggeredwith respect to the one next adjacent. Thus in Fig. 5, screens 2| andZiaare staggeredwhile screen-21b being offset with respect to screen 2|is not visible inthe drawing. The complete baffle comprises a righthandand a left-hand section, each section including three-screens, althoughit will be under.- stood that division of the baffle into sections isnot imperative, .andthat moreovermore than two sections may befoundconvenient from the standpoint of manufacture and maintenance. Moreover,the apertures in the screen may be slots disposed at anyangle'a'n'd'defined by bars orrod's set'into a frame.

Each screen is reinforced and supported at'its top, bottom, and center,respectively, by bent of the screens in this region being effected byPositioning of the screens depthwis'e through the screens 2|, 2la, and 2lb to the rear, and then through the screens again from the rear towardthe stack. Thus a two-stage screening or reclaiming function results tomaterially enhance the eiiiciency of the process. It will be obviousthat, if desired, the airstream may be directed by appropriate ductconstruction to pass through only one set of screens. Howevenunder somecircumstances it may be preferred to pass the air stream through-morethan two sets of screens. Nor is it necessary that the screens beoriented as shown, but one set may be at right angles or at some otherangle to another set.

The screens are preferably finished by porcelain enameling, this finishhaving been found to retain a maximum depositwhile permitting easyshaking-out thereof.

This latter step is attained by providing a vibrating-unit of anyconventional form-for example, an eccentric Weight carried on a motorshaft, the motor being bolted to a housing. The vibrator is shownschematically at 4] and is fixed to the bar 34 in any convenient way.Control of the motor of the vibrator may be by a push-button switch atthe front of the booth in order. that the operator may, at necessary andconvenient intervals, set the vibrator into motion to shakethe screens.Material thus dislodged from the screens falls to the fioor of thechamber l2, from which, by means of a door lt, the material may beremoved and reused. In Fig. 6 there is indicated a typical accumulationof deposit on the screen. By reason of the fiat surface of thelattice,the deposit tends to accumulate in an inverted pile, and in thisv waythe screen is able to gather and retain a large 'quantity of materialbefore shaking-out becomes sulting in removal -of an optimum amount ofmaterial from the air stream with minimum obstruction of air flow may beestablished.

my type of screen and arrangement thereof, eddy currents in and aroundthe apertures of the screen are dispensed with, and pick-up of ma.-

.-teria1from the air stream is far greater than Withsimihrmeansheretofore known.

; It will be recognized that some part of the en,-

amel'particles willsettle out from the air stream and drop to the fioorof the chamber 52. To in- With crease the reclaim from this source, thevelocity of the air stream may be reduced by making the dimension A-Bgreater than the dimension 14-0. A fifty per cent greater dimension hasbeen found suitable. Thus the slower moving air stream will deposit agreater yield within the chamber 12.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modifications may be made, and I therefore contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A spray booth for coating articles comprising a casing, a spraycoating chamber in the front of the casing for receiving an article tobe sprayed and coated, a collecting and recovery chamber in the casingin the rear of the coating chamber, a fan to produce a suction aircurrent through said chambers, a screen unit suspended between andseparating the two chambers, said screen unit comprising two or morevertical sheets of expanded metal spaced apart and with laterallystaggered openings and ribs, struts at the top and at the bottom of saidsheets and midway between secured thereto and holding said sheetsproperly positioned in said unit, the said unit being suspended from theupper struts in floating engagement with the casing, and a vibratorengaging the medial struts of the unit to vibrate said sheets todislodge material settling thereon from the said air current and to dropit in the said collecting and recovery cham her in dry condition.

2. A spray booth comprising a horizontal casing, a material reclaimingscreen vertically across said casing and dividing the same into a frontspray coating chamber and a rear collecting and recovery chamber, asupport in the coating chamber for an article to be spray-coated, aplate across said front chamber extending from the inside top of thecasing in advance of the screen to a line substantially midwayvertically of the said screen, an outlet stack connecting with the topof the casing over the portion definedby the said plate and screen, afan for causing a suction air current serially through the coatingchamber and the lower part of the screen below the said plate into andthrough the collecting and recovery chamber and reversely out throughthe upper part of the screen above the said plate and thence into thestack, means for mechanically vibrating said screen medially todischarge material settled thereon down into the collecting and recoverychamber, and a door in said collecting chamber to provide access theretofor the removal of said deposited material.

3. A spray booth comprising a horizontal casing, a material reclaimingscreen vertically across said casing and dividing the same into a frontspray coating chamber and a rear collecting and recovery chamber, asupport in the coating chamber for an article to be spraycoated, asloping plate across said front chamber extending from the inside top ofthe casing in advance of the screen to a line substantially midwayvertically of the said screen, an outlet stack connecting with the topof the casing over the portion defined by the said plate and screen, afan for causing a suction air current serially through the coatingchamber and the lower part of the screen below the said plate into andthrough the collecting chamber by a U-turn and reversely out through theupper part of the screen above the said plate and thence into the stack,said collecting and recovery chamber being larger in cross-sectionalarea than said lower part of the screen to slow up the current of air inits passage through the collecting and recovery chamber for thedepositing of material from the current itself, means for mechanicallyvibrating said screen to discharge material settled thereon down intothe collecting chamber, and a door in said collecting chamber to provideaccess thereto for the removal of said deposited material.

ALVA H. MEYER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 468,345 Hussey et al Feb. 9, 1892484,942 Rourke Oct. 25, 1892 1,319,706 Hedberg Oct. 28, 1919 1,368,426Foote Feb. 15, 1921 1,443,134 Klug Jan. 23, 1923 1,483,379 Reed Feb. 12,1924 1,576,121 Preble Mar. 9, 1926 2,045,519 Coutant June 23, 19362,232,561 Richards Feb. 18, 1941 2,257,516 Roche et a1 Sept. 30, 1941

